A fingerprint is an invariant feature of a human body, which is inborn and unique and is distinguished from other people. The fingerprint consists of a series of ridges and valleys on the skin surface of a finger end. Details of the ridges and the valleys generally include details of branches of the ridges, tail ends of the ridges, arches, tent-type arches, left spirals, right spirals, spirals or double spirals and the like, and these details decide uniqueness of a fingerprint pattern. A fingerprint identification element is generally used for personal identity authentication early; and currently, a photosensitive fingerprint identification element and a capacitive fingerprint identification element are widely applied and are well known.
In the photosensitive fingerprint identification element, generally there are provided a plurality of photosensitive thin film transistors and a plurality of signal lines respectively corresponding to the photosensitive thin film transistors and electrically connected with the photosensitive thin film transistors, and each photosensitive thin film transistor is electrically connected with a fingerprint identification chip by its corresponding signal line. In the case that a finger is positioned above the fingerprint identification element, intensity of light reflected to the photosensitive thin film transistors from the valleys of the finger is different from that of light reflected to the photosensitive thin film transistors from the ridges of the finger, so that light currents generated by the photosensitive thin film transistors are different in magnitude, and the fingerprint identification chip obtains the fingerprint pattern of the finger by detecting the light currents transmitted by the signal lines corresponding to the photosensitive thin film transistors.
In the fingerprint identification element, the valleys and the ridges of the finger need to be distinguished, and thus, a great number of photosensitive thin film transistors and a great number of signal lines connected with the photosensitive thin film transistors need to be arranged, resulting in a relatively complex structure of the fingerprint identification element.